The present invention relates to heat exchangers and, more specifically, relates to a metal foam heat exchanger having a surface for direct bonding to an electronic module.
Performance, reliability and packaging efficiency of advanced power electronics modules strongly depend on their ability to effectively remove dissipated energy. The effectiveness of the heat removal directly translates to lowering the junction temperatures of power semiconductor devices. Lower junction temperatures result in lower reverse saturation current of p-n junctions, higher switching speeds in MOSFET structures, increased reliability of metalized and bonded interfaces and a reduction in operating temperature.
Heat exchangers or heat sinks are metal heat radiators designed to remove heat from electronic components, particularly power transistor modules, by thermal conduction, convection, or radiation. Heat exchangers dissipate heat at a surface of an electronic module which may be generated by an internal junction of a semiconductor device within the module. Heat exchangers may also transfer heat from the location of device being cooled to another location by providing passages for a fluid coolant to flow through the heat exchanger.
In one known technique for cooling electronic modules, an oversized cold plate is attached to the module. The oversized cold plate reduces module temperatures by heat spreading and increasing the surface area for heat dissipation. However, the cold plate adversely increases the weight, volume, and cost of modules. Additionally, bonding the cold plate to the module requires the use of soft polymeric compounds which have high thermal resistance.
Accordingly, it is an object of the present. invention to provide a novel heat exchanger and method.
It is another object of the present invention to provide a novel integrated heat exchanger and thermal base plate assembly.
It is yet another object of the present invention to provide a novel metal foam for transferring heat from an electronic module.
It is still another object of the present invention to provide a novel metal foam having a surface for bonding directly to an electronic module where the metal foam provides a heat transfer path for the electronic module.
It is a further object of the present invention to provide a novel heat exchanging foam having a network of metal ligaments for cooling an electronic module by pulling heat away from the module through the metal ligaments and transferring heat in the metal ligaments to another location by directing a fluid coolant through interconnected voids which are formed by ligament surfaces.
It is yet a further object of the present invention to provide a novel heat exchanging metal foam having a network of metal ligaments forming elongated substantially ellipsoidal shaped voids oriented in one direction for directing a fluid coolant through the foam.
It is still a further object of the present invention to provide a novel heat exchanger having plural blocks of metal foam positioned in series on a surface of an electronic module where the blocks have variable thermal performance.